A general purpose engine of liquid-cooled type is used for example as a drive source for a power generator, a working machine, etc. Hereinafter, the general-purpose engine of liquid-cooled type, is referred to as “general-purpose liquid-cooled engine”. In the general-purpose liquid-cooled engine, by way of example, a cylinder block and a cylinder head are integrally formed and a cooling fan is disposed at the end of a crankshaft, with a carburetor and a muffler fitted to the side wall of the cylinder block.
A known general-purpose liquid-cooled engine is disclosed in e.g., Japanese Patent Application Laid-Open Publication No. H10-148134 (JP H10-148134 A) in which an engine cover collectively covers the entire engine including the cylinder block, the cylinder head, the cooling fan, the carburetor, and the muffler.
According to the general-purpose liquid-cooled engine disclosed in JP H10-148134 A, noise attributable to the engine is suppressed by collectively covering the entire engine by the engine cover.
Ordinarily, in order to enhance the noise-proof effect of the engine, it is desirable to suppress a large noise arising from a combustion chamber, the muffler, etc., among the structural parts of the engine.
In the engine disclosed in JP H10-148134 A, however, the entire engine including the cylinder block, the cylinder head, the cooling fan, carburetor, and the muffler is collectively covered by the engine cover. It is therefore difficult to properly cover the parts such, as the combustion chamber and the muffler generating a relatively high level of noise and to secure a sufficient noise-proof effect.
A known general-purpose engine of air-cooled type is disclosed in e.g., Japanese Patent Application Laid-Open Publication No. 2010-7599 (JP 2010-7599 A) in which to secure sufficient cooling properties, a cooling air is fed to the entire engine collectively covered by a cover. In this general-purpose engine, by collectively covering the entire engine by the cover, the cooling air fed into the interior of the cover can be delivered to the entire engine (especially, e.g., the cylinder block, the muffler, etc). As a result, the cylinder block, the muffler, etc. can be cooled by the cooling air delivered.
It is preferred for the above general-purpose liquid-cooled engine as well to be configured such that the entire engine is collectively covered by the cover in the same manner as the general-purpose engine of air-cooled type.
To collectively cover the general-purpose liquid-cooled engine by the cover, however, there is a need to effectively cool the coolant by feeding a cooling air to the radiator for liquid cooling, which necessitates a scheme different from that of the air-cooled general-purpose engine.